import React from 'react';
import ReactDOM from 'react-dom';
import './index.css';
// Square 组件渲染了一个单独的 <button>
// class Square extends React.Component {
//   // 向这个 class 中添加一个构造函数，用来初始化 state
//   // constructor(props) {
//   //   super(props);
//   //   this.state = {
//   //     value: null,
//   //   };
//   // }
//   render() {
//     return (
//       // <button className="square" onClick={function() {alert('click'); }}>
//       <button
//         className="square"
//         onClick={() => this.props.onClick()}>
//         {/* 数据通过 props 的传递，从父组件流向子组件 */}
//         {this.props.value}
//       </button>
//     );
//   }
// }
function Square(props) {
    return (
        <button className="square" onClick={props.onClick}>
            {props.value}
        </button>
    );
}

// Board 组件渲染了 9 个方块。
class Board extends React.Component {
    // constructor(props) {
    //     super(props);
    //     this.state = {
    //         squares: Array(9).fill(null),
    //         xIsNext: true,
    //     };
    // }

    renderSquare(i) {
        // 传递一个名为 value 的 prop 到 Square 当中
        return (
            <Square
                // value={this.state.squares[i]}
                value={this.props.squares[i]}
                // onClick={() => this.handleClick(i)}
                onClick={() => this.props.onClick(i)}
            />
        );
    }

    render() {
        // const winner = calculateWinner(this.state.squares);
        // let status;
        // if (winner) {
        //     status = 'Winner' + winner;
        // } else {
        //     status = 'Next player: ' + (this.state.xIsNext ? 'X' : 'O');
        // }

        // const status = 'Next player: '+(this.state.xIsNext?'X':'O');
        return (
            <div>
                {/*<div className="status">{status}</div>*/}
                <div className="board-row">
                    {this.renderSquare(0)}
                    {this.renderSquare(1)}
                    {this.renderSquare(2)}
                </div>
                <div className="board-row">
                    {this.renderSquare(3)}
                    {this.renderSquare(4)}
                    {this.renderSquare(5)}
                </div>
                <div className="board-row">
                    {this.renderSquare(6)}
                    {this.renderSquare(7)}
                    {this.renderSquare(8)}
                </div>
            </div>
        );
    }
}

// Game 组件渲染了含有默认值的一个棋盘
class Game extends React.Component {
    constructor(props) {
        super(props);
        this.state = {
            history: [{
                squares: Array(9).fill(null),
            }],
            stepNumber: 0,
            xIsNext: true,
        }
    }

    render() {
        const history = this.state.history;
        // const current = history[history.length - 1];
        const current = history[this.state.stepNumber];
        const winner = calculateWinner(current.squares);

        const moves = history.map((step, move) => {
            const desc = move ?
                'Go to move #' + move :
                'Go to game start';
            return (
                <li key={move}>
                    <button onClick={() => this.jumpTo(move)}>
                        {desc}
                    </button>
                </li>
            );
        });

        let status;
        if (winner) {
            status = 'Winner: ' + winner;
        } else {
            status = 'Next player: ' + (this.state.xIsNext ? 'X' : 'O');
        }
        return (
            <div className="game">
                <div className="game-board">
                    <Board
                        squares={current.squares}
                        onClick={(i) => this.handleClick(i)}
                    />
                </div>
                <div className="game-info">
                    <div>{status}</div>
                    <ol>{moves}</ol>
                </div>
            </div>
        );
    }

    handleClick(i) {
        const history = this.state.history.slice(0, this.state.stepNumber + 1);
        const current = history[history.length - 1];
        const squares = current.squares.slice();
        if (calculateWinner(squares) || squares[i]) {
            return;
        }
        squares[i] = this.state.xIsNext ? 'X' : 'O';
        this.setState({
            // squares: squares,
            history: history.concat([{
                squares: squares,
            }]),
            stepNumber: history.length,
            xIsNext: !this.state.xIsNext,
        });
    }

    jumpTo(step) {
        // alert(step)
        this.setState({
            stepNumber: step,
            xIsNext: (step % 2) === 0,
        });
    }
}

function calculateWinner(squares) {
    const lines = [
        [0, 1, 2],
        [3, 4, 5],
        [6, 7, 8],
        [0, 3, 6],
        [1, 4, 7],
        [2, 5, 8],
        [0, 4, 8],
        [2, 4, 6],
    ];
    for (let i = 0; i < lines.length; i++) {
        const [a, b, c] = lines[i];
        if (squares[a] && squares[a] === squares[b] && squares[a] === squares[c]) {
            return squares[a];
        }
    }
    return null;
}

// ========================================

ReactDOM.render(
    <Game/>,
    document.getElementById('root')
);